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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dmitry Vyukov <dvyukov@google.com>,
        Ying Xue <ying.xue@windriver.com>,
        Jon Maloy <jon.maloy@ericsson.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.9 23/71] tipc: use lock_sock() in tipc_sk_reinit()
Date:   Mon,  7 Jan 2019 13:32:52 +0100
Message-Id: <20190107105334.125764155@linuxfoundation.org>
In-Reply-To: <20190107105330.280153213@linuxfoundation.org>
References: <20190107105330.280153213@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Cong Wang <xiyou.wangcong@gmail.com>

[ Upstream commit 15ef70e286176165d28b0b8a969b422561a68dfc ]

lock_sock() must be used in process context to be race-free with
other lock_sock() callers, for example, tipc_release(). Otherwise
using the spinlock directly can't serialize a parallel tipc_release().

As it is blocking, we have to hold the sock refcnt before
rhashtable_walk_stop() and release it after rhashtable_walk_start().

Fixes: 07f6c4bc048a ("tipc: convert tipc reference table to use generic rhashtable")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Ying Xue <ying.xue@windriver.com>
Cc: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/tipc/socket.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2281,11 +2281,15 @@ void tipc_sk_reinit(struct net *net)
 			goto walk_stop;
 
 		while ((tsk = rhashtable_walk_next(&iter)) && !IS_ERR(tsk)) {
-			spin_lock_bh(&tsk->sk.sk_lock.slock);
+			sock_hold(&tsk->sk);
+			rhashtable_walk_stop(&iter);
+			lock_sock(&tsk->sk);
 			msg = &tsk->phdr;
 			msg_set_prevnode(msg, tn->own_addr);
 			msg_set_orignode(msg, tn->own_addr);
-			spin_unlock_bh(&tsk->sk.sk_lock.slock);
+			release_sock(&tsk->sk);
+			rhashtable_walk_start(&iter);
+			sock_put(&tsk->sk);
 		}
 walk_stop:
 		rhashtable_walk_stop(&iter);